The Sun reports that the Belgium international was given permission by the Premier League side to train with the Belgian champions as his preseason programme with the Blues does not start until Monday.

Lukaku has spent the last two seasons away from Stamford Bridge on loan, scoring 17 goals for West Brom during the 2012-13 campaign before netting 16 for Everton last term.

Chelsea boss Jose Mourinho will reportedly give Lukaku an opportunity to prove himself during the club's preseason friendlies before deciding on his future, with his assistant Steve Holland confirming on Saturday: "The plan is that [Lukaku] will join up with us at some stage during the second week when we are in Holland."